On-off sprinkler

ABSTRACT

An improved sprinkler for a fire protection sprinkler system in which the sprinkler opens to discharge water at one temperature and closes to stop the flow of water at a lower temperature. A pilot valve is actuated by a bimetal disc which also resiliently biases the pilot valve in a closed position. The bimetal disc has a snap action resulting in better control of the &#34;on&#34; and &#34;off&#34; temperatures of the sprinkler. A thermal delay for closing is obtained by the hysteresis which is designed into the bimetal disc.

BRIEF SUMMARY OF THE INVENTION

Conventional sprinklers for fire sprinkler systems are single operationdevices wherein a heat responsive member releases a plug which ispositioned to prevent the flow of water from the sprinkler. When theplug is released, water flows against a deflector which disperses thewater in a desired pattern. Such a sprinkler must be replaced after afire and the entire sprinkler system must be shut off to replace thesprinkler.

Many attempts have been made to produce a sprinkler which would shutitself off after a fire is extinguished. Such a sprinkler would conservewater because the flow of water is shut off, and it would be ready tooperate immediately if the fire should start up again. In one design afluid balanced piston valve is utilized to control flow of theextinguishing fluid from the sprinkler. A pilot valve controls the fluidbalance and, thus, the position of the piston valve in either an open ora closed position. The pilot valve in turn is positioned by a leafbimetal member which is responsive to atmospheric temperature. (See U.S.Pat. No. 917,292.)

The present invention provides an improved pilot valve arrangement inwhich a bimetal snap disc is used to position the pilot valve. Thebimetal disc is positioned to load or resiliently bias the pilot valvetoward a closed position. A hysteresis is built into the disc and isutilized to move the pilot valve to its closed position at a temperaturelower than that at which the pilot valve is moved to an open position.With this built-in thermal delay, the sprinkler is not shut off untilthe surrounding temperature is low enough to assure that the fire isout.

An object of the present invention is to provide an improved on-offsprinkler having a fluid balanced main valve and a pilot valve forcontrolling the fluid balance on the main valve, in which the operatingtemperature of the sprinkler is controlled to close tolerances for bothan "on" operation and an "off" operation.

Another object is to provide an improved on-off sprinkler in which thepilot valve is moved with a snap action.

Another object is to provide an improved on-off sprinkler in which thepilot valve is resiliently biased in a closed position at temperaturesbelow a predetermined operating temperature by a bimetal disc.

Another object is to provide an improved on-off sprinkler which opens atone predetermined temperature and closes at a second, lowerpredetermined temperature.

Other advantages and features of the invention will be apparent from thefollowing description and accompanying drawings.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a sectional, front view of an on-off sprinkler embodying thepresent invention, in which the sprinkler is shown in an "off" position;

FIG. 2 is a sectional, front view of the sprinkler shown in FIG. 1, inwhich the sprinkler is shown in an "on" position; and

FIG. 3 is a partially sectioned right side view of the sprinkler shownin FIG. 2.

Referring first to FIG. 1, the improved sprinkler embodying the presentinvention is shown in a pendent position. The sprinkler has a body 10defining a circular, threaded opening 12, a flow passage 14, and anoutlet 16, spaced from the opening 12. The body 10 is preferably formedby a casting of a suitable material such as bronze. An inner wall 18cooperates with an inner wall 22 and the outer wall of the body 10 todefine a cylindrical chamber 20, the axis of which passes through thecenter of the threaded opening 12. The threaded opening 12 has adiameter which is at least as great as the diameter of the cylindricalchamber 20. The second inner wall 22, which is positioned at the lowerend of the chamber 20, cooperates with a lower wall 24 of the body 10 todefine a threaded opening 26 and a chamber 28. The chamber 28 is alignedwith a passage 30 and communicates through the passage 30 with thechamber 20 and the chamber 28 communicates with the flow passage 14through a passage 32 in the wall 18. The cylindrical surface 21 of thechamber 20 is finished smooth, and a smooth seating surface is formed onthe area 31 of the wall 18 surrounding the entrance to the passage 32.

An inlet member 34 has an externally threaded end 35 which mates withthe threaded opening 12 to secure the inlet member 34 in the opening 12of the body 10. A second externally threaded end 36 is of a size whichis suitable for connecting the sprinkler to a sprinkler piping system.

The inlet member 34 further has a cylindrical passage 38 which providesan axial passage for fluid through the inlet member to the flow passage14. The diameter of the flow passage 38 is less than the diameter of thechamber 20. An annular surface 39 at the inner end of the inlet member34 is smooth and functions as a seating surface, as will be explainedhereinafter.

A piston assembly 40 is received in the chamber 20, and closes the upperend of the chamber 20. The piston assembly 40 comprises a piston 42having a first cylindrical portion 44 and a second, smaller cylindricalportion 46. An axial bore 48 through the second cylindrical portion 46and axial counterbores 50 and 52 in the first cylindrical portion 44provides a passage axially through the piston 42.

The first cylindrical portion 44 of the piston 42 has a diameter whichis sized to be slideably received in the passage 20 of the inlet member34. The second cylindrical portion 46 of the piston 42 has a diameterwhich is sized to be slideably received in the cylindrical chamber 38.In this manner, the piston 42 is mounted for axial movement toward andaway from the inlet member 34. The second cylindrical portion isprovided with ports 53 positioned to permit a fluid to pass from theaxial passage 38 to the flow passage 14 only when the piston 42 ispositioned in its lower position of travel.

An O-ring 54 in a groove 56 in the outer surface of the firstcylindrical portion 46 prevents fluid flow through the annular spacebetween the wall 21 and the first cylindrical portion 44.

An annular lip 70 projects from the surface which connects the outersurface of the first and second cylindrical portion 46 to form, with thecylindrical portion 46, an annular groove 72. This groove 72 receives anO-ring 74 which engages and seats against the surface 39 of the inletmember 34 when the piston 42 is moved axially toward the inlet member toprovide a fluid seal.

A restriction member 82 and a strainer 84 are secured in the counterbore50 of the piston 42 by a retaining ring 80. The restriction member 82has an orifice 86 to control fluid flow from the inlet port to thechamber 20. The strainer 84 will prevent the obstruction of the orifice86 by foreign materials which may enter the sprinkler from the sprinklersystem to which the sprinkler is connected. The strainer 84 has a domedportion to provide an increased area and flow passages through thestrainer. Both strainer 84 and the restriction member 82 are formed ofnon-corrosive materials such as brass or bronze.

A coil spring 90 is positioned between the retaining ring 80 and theinner wall 22 to provide a resilient bias to the piston 40 toward theinlet member 34. The lower end of the spring 90 fits into a recess 92 inthe wall 22 to keep the spring in position.

It will be noted that the area of the piston assembly 40, which can beacted on by fluid pressures in the passage 38, is considerably less thanthe area of the piston assembly which can be acted on by fluid pressuresin the chamber 20, so that when the inlet fluid pressure and the fluidpressure in the chamber 20 are equal, the balance of fluid pressureswill hold the piston 42 in its closed position.

In accordance with the present invention, an improved pilot valveassembly 100 is provided for controlling fluid flow from the chamber 20,the passage 30, the chamber 28, and through the passage 32 to the flowpassage 14. The pilot valve assembly 100 comprises a retainer member 102having an externally threaded cylindrical portion 102 which is of asuitable size for engaging the threads of the threaded opening 26 of thebody 10. The retainer member 102 has a radial flange portion 106 whichis positioned a short distance away from the body 10 when the retainermember 102 is threaded into the opening 26. A bore 108 extends axiallythrough the retainer member 102.

A pilot valve 110 having a cylindrical portion 112 fits loosely foraxial movement in the bore 108 and in the cavity 28. An O-ring 116 fitsin a recess 118 in the outer surface of the cylindrical portion 112 toprovide a fluid seal between the cylindrical portion 112 and the surfaceof the bore 108.

The valve 110 has an axial length which permits the inner end 120 totouch the seat surface 31 surrounding the passage 32. An O-ring 122 inan annular groove 124 in the surface of the end 120 provides a fluidseal with the seat surface 31 when the valve 110 is urged axiallythereof toward the seat surface 31.

A bimetal disc 126 is centrally connected to the outer end of the valve110 by a drive screw 128 which passes through a central opening in thedisc 126 and into a drilled hole in the outer end of the valve 110. Theedges of the disc 126 are secured to the radial flange 106 by drivescrews 132. Preferably, the area of contact of the drive screws 132 withthe bimetal disc is held to a minimum so that heat flow from the bimetaldisc 126 to the flange 106 is at a minimum. A thermal insulator (notshown) could be installed between the contact points of the disc withthe drive screws 132, if desired.

A conventional deflector 130 is spaced from the outlet 16 of the flowpassage 14 and perpendicular to the projected axis of the flow passage14 by a yoke 131 which is generally U-shaped.

The free ends of the yoke 131 are serrated and secured in openings 134which are drilled therefor in the body 10 by swaging, as at 136, thebody 10 against the serrations, as seen in FIG. 3. The deflector 130 issecured to the yoke 131 by a rivet 138.

In accordance with the present invention, the bimetal disc 126 is cuppedand is designed to move with a snap action toward a reverse cup shape atone temperature, for example 185° F, and when in the reversed shape, toreturn to its original shape at a second, lower temperature, for example100° F. Further, the bimetal disc 126 is positioned with its concavesurface facing the pilot valve 110 and is urged against the valve 110 toresiliently bias the valve 110 toward its closed position.

To compensate for the stress loading of the bimetal disc 126, atemperature rating is selected for the bimetal disc 126 which is higherthan the desired operating temperature. In order to position the pilotvalve assembly 100 in the body 10, to provide a resilient bias on thevalve 110 and to obtain operation of the pilot valve at a desiredtemperature, the assembly 100 and the body 10 are put in a heatedenvironment at the desired operating temperature of the sprinkler. Theretainer member 102 is threaded into the opening 26 and tightened untilthe O-ring 122 is pressed against the seating surface 31 with sufficientpressure at the desired operating temperature of the sprinkler to causethe bimetal disc 126 to snap to the position to open the pilot valve.The pilot valve assembly is now installed in its proper position withthe desired bias provided by the bimetal disc 126.

An anaerobic plastic, such as "Loctite" No. 70, is applied to thethreads of the retainer member 70 prior to its being put in the heatedoven for installation. This anaerobic plastic will harden to lock thethreads in this position.

It will be recognized that the pilot valve 110 can be resiliently biasedtoward its closed position by a separate spring and that it is notnecessary to obtain the bias from the bimetal disc 126.

In operation, the sprinkler is installed in a sprinkler system in apendent position. When the water is turned on, water flows into thepassage 38, the axial bore 48, through the strainer 84 and the orifice86 in the restriction member 82, to fill the chambers 20 and 28. Thepilot valve 110 is held in a closed position by the resilient force ofthe bimetal disc 126 so that no water discharges through the passage 32.When the chambers 20 and 28 have filled with water, equal fluid pressureis established above and below the piston 42.

Because the area of the piston assembly 40 which is exposed to fluidpressure in the chamber 20 is greater and produces a greater force onthe assembly 40 tending to move the piston assembly axially toward theinlet member 34 than the area and the force which is produced by thefluid tending to move the piston assembly 40 axially away from the inletmember 34, the O-ring 74 is pressed tightly against the surface 39 toclose the sprinkler.

In the event of a fire, the temperature surrounding the bimetal disc 126will rise. As the bimetal disc 126 reaches its operating temperature,the disc snaps to a reverse cup shape, moving the pilot valve 110 withit and moving the O-ring 122 off its seat 31. Immediately waterdischarges from the chamber 28, through the passage 32, thereby loweringthe pressure sufficiently in the chamber 20 so that its force againstthe area of the piston assembly 40 becomes less than the force of fluidin the inlet member. Restriction member 82 prevents fluid pressure frombuilding up in chamber 20. At a point, the fluid pressure against thetop of the piston assembly is sufficient to overcome the force of thespring 90 causing piston assembly 40 to move axially downward to an openposition, as shown in FIG. 2.

With the piston assembly in this position water flows through ports 53,and along the flow passage 14 to discharge against the deflector 130. Asthe deflector is below the bimetal disc 126 with the sprinkler in apendent position, the discharging water will not cool the bimetal disc126 as long as the fire continues to burn.

After the fire is extinguished, the bimetal disc 126 cools and, uponreaching its lower operating temperature, snaps to its original positionto move the pilot valve 110 to a position to close the passage 32. Asthe chambers 28 and 20 fill with water, the pressure in the chamber 20increases until it produces a force which moves the piston assembly 40axially toward the inlet member 34 to stop further flow through thesprinkler.

The invention is not intended to be limited to the particularembodiments thereof illustrated and described above, but only by thefollowing claims and their equivalents.

We claim:
 1. A water sprinkler device for a fire protection systemcoupled to a pressurized fluid supply line; comprising in combination:asprinkler body having an annular inlet portion adapted for coupling tosaid fluid supply line; means providing an inner wall for dividing saidsprinkler body into a first bifurcation, having an outlet portion thatdefines a main fluid flow passageway between said inlet portion and saidoutlet portion, and a second bifurcation that defines a control chamber;a deflector mounted adjacent said outlet portion to deflect fluid flowtherethrough; means providing a valve seating surface abutting saidinlet portion at the junction of said bifurcations; a main valvedisposed in a direction downstream from said seating surface and havinga valve seat mounted in opposed relation to said seating surface so asto oppose fluid pressure from said inlet portion that tends to causesaid valve seat to separate from said seating surface to open saidvalve; said main valve being slideable into said control chamber forcontrolling fluid flow through said main passageway while maintainingsaid control chamber blocked to fluid flow from said outlet portion; anaperture formed substantially centrally in said main valve to define acontrol passageway that couples fluid from said inlet portion to saidcontrol chamber; said main valve exhibiting a first surface areadisposed toward said control chamber that is greater than a secondsurface area disposed toward said inlet portion to provide a greatermain valve closing pressure than opening pressure; means providing anoutlet port from said control chamber to release fluid pressuretherefrom to open said main valve; pilot valve means having a valvemember mounted to control fluid flow through said outlet port andincluding a bimetallic disc centrally connected to said valve member,and means for securing the peripheral edges of said bimetallic discagainst movement relative to said sprinkler body so as to flex said discin a manner to resiliently bias said valve member to close said outletport, said disc responding to temperature rise to snap to an oppositeflexure to open said outlet port to release fluid from said controlchamber to open said main valve.
 2. The combination in accordance withclaim .[.4.]. .Iadd.1 .Iaddend.wherein said bimetallic disc exhibits ahysteresis effect wherein said disc flexes in one direction to open saidpilot valve means upon the occurrence of a first predeterminedtemperature but flexes in the reverse direction to close said pilotvalve means upon the occurrence of a second temperature lower than saidfirst predetermined temperature. .Iadd.
 3. A water sprinkler device fora fire protection system coupled to a pressurized fluid supply line;comprising in combination:a sprinkler body having an annular inletportion adapted for coupling to said fluid supply line; means providingan inner wall for dividing said sprinkler body into a first bifurcation,having an outlet portion that defines a main fluid flow passgewaybetween said inlet portion and said outlet portion, and a secondbifurcation that defines a control chamber; a deflector mounted adjacentsaid outlet portion to deflect fluid flow therethrough; means providinga valve seating surface abutting said inlet portion at the junction ofsaid bifurcations; a main valve disposed in a direction downstream fromsaid seating surface and having a valve seat mounted in opposed relationto said seating surface so as to oppose fluid pressure from said inletportion that tends to cause said valve seat to separate from saidseating surface to open said valve, said main valve being slideable intosaid control chamber for controlling fluid flow through said mainpassageway while maintaining said control chamber blocked to fluid flowfrom said outlet portion, an aperture formed substantially centrally insaid main valve to define a control passageway that couples fluid fromsaid inlet portion to said control chamber; said main valve exhibiting afirst surface area disposed toward said control chamber that is greaterthan a second surface area disposed toward said inlet portion to providea greater main valve closing pressure than opening pressure, meansproviding an outlet port from said control chamber to release fluidpressure therefrom to open said main valve, pilot valve means having avalve member mounted to control fluid flow through said outlet port andincluding a bimetallic disc operatively connected to said valve member,said disc responding to temperature rise to snap in a direction to opensaid outlet port to release fluid from said control chamber to open saidmain valve. .Iaddend..Iadd.
 4. The combination in accordance with claim3, wherein said bimetallic disc exhibits a hysteresis effect whereinsaid disc flexes in one direction to open said pilot valve means uponthe occurrence of a first predetermined temperature but flexes in thereverse direction to permit closing of said pilot valve means upon theoccurrence of a second temperature lower than said first predeterminedtemperature. .Iaddend..Iadd.
 5. The combination in accordance with claim3, wherein the bimetallic disc is mounted externally of the sprinklerbody and at a position above the deflector, whereby the disc is exposedto ambient temperature and does not come into contact with dischargefluid. .Iaddend..Iadd.
 6. The combination in accordance with claim 3,wherein the pilot valve means additionally comprises a retainer memberhaving a radial flange portion spaced from the sprinkler body, saidflange portion protects the disc from discharge fluid. .Iaddend..Iadd.7. A water sprinkler device for a fire protection system coupled to apressurized fluid supply line, comprising in combination:a sprinklerbody having an annular inlet portion adapted for coupling to said fluidsupply line; means providing an inner wall for dividing said sprinklerbody into a first bifurcation, having an outlet portion that defines amain fluid flow passageway between said inlet portion and said outletportion, and a second bifurcation that defines a control chamber; adeflector mounted adjacent said outlet portion to deflect fluid flowtherethrough; means providing a valve seating surface abutting saidinlet portion at the junction of said bifurcations; a main valvedisposed in a direction downstream from said seating surface and havinga valve seat mounted in opposed relation to said seating surface so asto oppose fluid pressure from said inlet portion that tends to causesaid valve seat to separate from said seating surface to open saidvalve, said main valve being slideable into said control chamber forcontrolling fluid flow through said main passageway while maintainingsaid control chamber blocked to fluid flow from said outlet portion, anaperture formed substantially centrally in said main valve to define acontrol passageway that couples fluid from said inlet portion to saidcontrol chamber; said main valve exhibiting a first surface areadisposed toward said control chamber that is greater than a secondsurface area disposed toward said inlet portion to provide a greatermain valve closing pressure than opening pressure, means providing anoutlet port from said control chamber to release fluid pressuretherefrom to open said main valve, a pilot valve means for closing saidoutlet port; and temperature responsive means for controlling the pilotvalve means including a bimetallic disc which exhibits a hysteresiseffect by flexing in one direction to open said pilot valve means andrelease fluid from said control chamber upon the occurrence of a firstpredetermined temperature and flexing in a reverse direction to allowclosure of said pilot valve means upon occurrence of a secondtemperature lower than said first predetermined temperature. .Iaddend.